Apparatus for bridging a well conduit

ABSTRACT

An illustrative embodiment of the present invention in throughtubing bridge plugs includes a body member carrying an expansible bridging element, a pump and receptacle assembly releasably coupled to the body member and adapted to contain a cementitious material that can be displaced from the receptacle to expand the bridging element, a vent passage through the body member to enable fluid movement within the well bore without disturbing the cementitious material as it hardens, and valve means automatically operable after a preselected time delay for closing off the vent passageway.

United States Patent [72] Inventor Nevyl G. Owens Houston, Tex.

21 Appl. No. 819,515

[22] Filed Apr. 22, 1969 [45] Patented Jan. 19, 1971 [7 3] Assignee Schlumberger Technology Corporation New York, N.Y.

a corporation of Texas [54] APPARATUS FOR BRIDGING A WELL CONDUIT 14 Claims, 11 Drawing Figs [52] U.S.Cl 166/187, I 166/188 [51] Int.Cl .6 E21b23/06, EZlb 33/127 [50] Field ofSearch 166/187,

[56] I References Cited UNITED STATES PATENTS 2,978,029 4/1961 OReilly et a1. 166/1 87X 3,460,618 8/1969 Blagg l l 166/187X 3,460,624 8/1969 Aitken et a1. 166/187X 3,489,216 1/1970 Armstrong et al. 166/126 Primary ExaminerDavid H. Brown Attorneys-Ernest R. Archambeau, J r., William J. Beard,

Donald H F idler, David L. Moseley, Edward M. Roney and William R. Sherman PATENTED JAN 1 9191:

SHEET 1 BF 4 F/Gi Navy! 6. Owens IN VENTOR FIG. 2A

A TTORNEY FIG.8

FIG.7

Navy! 6. Owens INVENTOR A TTORNE Y PATENTEU JAN 1 9 I9?!" sum 3 OF 4 BY WW 7 mtmemm m "sum u 0F 4 J Ne vyl G. Owens IN VE N TOR FIG. 10

ATTORNEY Fla 1 APPARATUS FOR BRIDGING A WELL CONDUIT The present invention relates generally to plugs adapted to form a pressure bridge in a well conduit (either cased or open hole), and more specifically to a new and improved throughtubing bridge plug apparatus havinga vent passage which is automatically closed after a preselected time lapse.

It is often desirable to form a pressure bridge or plugging a well conduit below the lower end of a relatively small diameter pipe or tubing string extending therein. This can be accomplished by utilizing one of the various embodiments of through-tubing bridge plugs disclosed in the copending Hart et al. application Ser. No. 63 l',09l now PAT. No. 3,460,625 entitled "Methods and Apparatus for Bridging a Well Conduit tiled Apr. l4, I967 and assigned to the assignor of the present invention. Basically these devices are adapted to be run into the well on electrical cable or wireline and are comprised of a central support carrying an inflatable packing, element and coupled to a receptacle containing an initially fluent medium, such as cement slurry, which is capable of subsequently hardening. The device is sized and arranged'to be lowered into the well through a tubingstring and to'. a setting point below the lower end thereof, whereupon a positive displacement pump can be actuated upon signal from the surface to expand the packing element so as to providea bridge across the well conduit. A column of cement slurry is also deposited on top of the bridge and allowed to harden to provide a substantial cement plugwhich functions to prevent fluid flow in either longitudinal direction. i

. As fully described in the aforementioned Han et al. application, a vent passage is provided in the ,support extending an elongated body member carrying an inflatable packer means that is adapted for a wide range of expansion upon inflation. Releasably coupled to the body member is areceptacle which contains cement slurry or. the like. anda pump device that can be operated remotely or from the earth's sur- 'face. The pump functions to positively displace sufficient cement slurry into the packer means to expand it into engagement with the surrounding well conduit wall, whereupon the balance of the slurry contained within the receptacle is I when the pump has displaced all the cement slurry from the between locations in'communication with-the well bore above and below the packing element to enable fluids moving within the casing to pass through the cement column without disturbing it during the hardening process. Otherwise, such fluid movement can cause channels through the cement which remain after it hardens and destroy the ability of the plug to hold pressure. After the cement is hardened. the vent passageway is closed by either lowering a valve elementfrom the surface and positioning it to close ofl the passageway, or by manipulating from the surface a valve element in the tool to a condition closing the passagewayL-Although a through-tubing bridge plug apparatus in accordance with the concepts disclosed in the Hart et al. application has been found'to be quite satisfactory, the valve closing operation requires either a subsequent trip into the well to close the valve, or requires leaving the pump and receptaclein the well for" the period of time necessary for the cement column to harden. Both procedures involve a certain amount of time delay that ties up men and equipment at the well sitewith attendant expense. 7

It is accordingly the primary object of the present invention to provide new and improved apparatus of the type described above, and wherein the vent passageway is automatically closed after a preselected time lapse calculated to enable the cement column to harden. e o

In order that the bridge plug setting operation be carried out with maximum dispatch. it is desirable to be able to withdraw the pump and cement receptacle from the well bore soon after setting the plug. In the past. a certain amount of delay was involved to enable the cement within and on top of the packer to harden so that an upward pull on the wireline could be usedto release the pump and receptacle. Otherwise, the plug was not sufficiently anchored to permit such upward force to be applied. f n i It is accordingly a further object of the present invention to provide a new and improved through-tubing bridge plug apparatus having a releasable connection between the bridge plug and the cement receptacle which is automatically released after the pump and receptacle have performed their functions so that they can be immediately withdrawn from the receptacleso that the pump and receptacle can be withdrawn to thesurface without waiting for a hardened condition of the cement to transpire. r r

A passageway extends from a'location in communication with the well bore below the packer means to a location in communication withthefwell bore above the column to provide a flow course through which well fluids can pass temporarily without disturbingthe cement as it hardens. A normally open valve means is adapted to close off the passageway, and is operated to .doso .by a means which is restrained, however, by a time delay. Accordingly, the valve means cannot move into a condition closing off the passageway until the expiration of a preselected time interval which is sufficient to enable the cement to harden and provide an effective plug. j I

The invention has other objects advantages which will become apparent in connection with the following detailed description. The novel features ofthe present invention being set forth with particularly in the appcndcd claims; the present invention. both as to its organization and manner of operation.

may best be understood byway of illustration and example of an embodiment thereof when taken in conjunction with the accompanying drawings. in which:

.FIG. I, is a schematic view of an apparatus incorporating the principles of the present inventionbeing lowered into a well through tubing; v v

FIGS. 2A and 2B are longitudin'al sectional views to illustrate the general structural details of the apparatus shown in F IG. 1, FIG. 28 forming a lower continuation of FIG. 2A;

. FIG. 3 is a detailed cross-sectional view of the latch construction connecting the receptacle to the bridge plug body;

FIG. 4 IS A cross section taken on line 4-4 of FIG. 3

FIG. 5 is an enlarged sectional viewof the vent valve structure, actuator, and timer mechanism;

FIG. 6 is a side view of the timer mechanism; 7

FIG. 7 is an isometric view of the shaft of the timer main wheel showing the release cord attached thereto;

FIG. 8 illustrates an alternate embodiment of the timer;

FIG. 9 is a sectional view of the lower portion of the apparatus after the packing element has been expanded to provide a bridge in the well; and a FIG. 10 is a view similar to FIG. 9 but with various parts operated for depositing a column of cement on the top of the P a- Referring initially to FIG. I, A through-tubing bridge plug assembly which is described to illustrate the principles of the present invention is shown being lowered at the end of a wireline W through a tubing string'l toward a selected setting point with a well casing C below the lowerend of the tubing string. The assembly includes a dump -bailer actuator or pump section 10 coupled to the upper end of a positive displacement dump bailer or receptacle II. The receptacle II is, in turn, releasably connected to the upper end of an elongated body member 12 which carries an inflatable packer element 13. The packer element I3 may comprise an inflatable packing sleeve or bag which is normally collapsed during lowering and which can be expanded to several times its collapsed size in order to bridge the well bore. A valve and timer assembly I4 forms the lower part of the apparatus. The entire assemblyis constructed and arranged to pass downwardly through, for example, a 1 25/32 inch bore. and can be operated to pacl off or bridge a range of easing sizes from 3% inches to 7% inches.

Referring now to H0. 2A for further detail, the dump bailer actuator section includes a tubular case 17 having a longitudinally extending chamber 18 therein. A piston 19 is movably received within the chamber 18, and a rod 20 connected to the piston extends downwardly through a bore 21 which opens axially into the chamber 18. The upper portion of the chamber 18 is arranged to receive a suitable hydraulic fluid, and a coil compression spring 22 is arranged in the lower portion of the chamber to urge thepiston 19 and the rod 29 1 upwardly. Several side ports 23 in the wall of the case 17 'below the piston 19 enable fluid pressures within the chamber 1 18 to be balanced with hydrostatic well fluid pressures as the may be constituted by a two-p'ice assembly including a. tubular valve housing 60and a packer mandrel .611. which are cou pled together byscrews 62 or the-like:gThe'through-bore of tool is lowered into a fluid filled well bore. To permit placement of hydraulic fluid into the upper portion of the chamber 18, a one-way check valve 24 in an entry passage 25 is pro vided. An exit passage 26 extends from the chamber 18 to the exterior of the case 17, and has a remotely controllable valve 27 therein, such as a conventional solenoid-operated valve, which normally prevents discharge of hydraulic fluid from the chamber. With this condition of parts, the piston 19 and the 0d 20 cannot move upwardly under the influence of the upward force being exerted by the coil spring 22.

The piston rod 20 extends downwardly through the bore 21 g o a location within a recess 30 where it can operate a latch device.- The latch device includes a plurality of upwardly extending, inwardly biased spring fingers 31, which terminate in 5 enlarged head portions 32. Whenthe parts are in the relative positions shown in HQ. 2A, the head portions 32 held outwatery by the rod 20 in engagement with a shoulder 33 formed the"recess 30. However, it will be appreciated that removal tl't -rOdZO from behind the head portions 32 will permit 5 them to' spring inwardly and out of engagement with the -""shoulder 33. The retention'and release of the spring fingers 31 from the recess 30 controls the operation of the positive displacement dump bailer section 11.

The dump bailer section includes a cylinder 35 connected at its upper end to the control section 10. The lower end of the housing 35 is releasably connected by a latch device 36 to upper end of the body member 12. The cylinder has a bore .37

' in which a weighted body 38 is movable. The weighted body 38 can take the form of an elongated tubular member having a rod 39 extending upwardly from its upper end, the rod having the previously-described spring fingers 31 connected to its upper end and extendinginto the recess 30. A coil spring 40 can surround the rod 39 with its upper end pressing against the upper end of the bore 37' and its lower end pressing against the upper surface of the weighted body 38,

Also positioned within the bore .of the cylinder 35 and spaced downwardly from the lower end of the weighted body 38 is a piston assembly 41 having an elastorner swab" cup 42 upper end thereof is form the valve housing is provided-'withya steppcdtdiamete An annular valve element 63 is ummy-heaved within-the housing 60, the valve element being in'the' fbr'mzof a-sleevepiston having art-annular head 64 which is sealediwithi'respect-to wall surface 65 by an O-ring 66. The valve elemertt 63 furtherghas a tubular portion 67 extending downwardlyinto the :small diameter bore portion 68. The annular housing space 70 below the head 64 is placed in communication with the well annulus by one or more radially extending ports 71. A shear ,pin 72 or the like extends through the wall of the housing 60 and engages within a recess on the tubular portion 67 in order normally to retain the valve element 63 is the p sition shown in FlG. 2B. 1v 1 ,The valve element 63 further has a central bore 73 extending throughout its length which sealingly receives an enlarged portion 74 of an elongated vent tube 75. The e nlar'ged portion 74 is sealed against the bore wall of the valve ele'ment63 by an O-ring 76. The lower end of the vent tube 75 is seated'and sealed within a counterbore 77 in the mandrel 61, whereas the ejdi'n a' tee configuration 'toprovide oppositely disposedjports .78 and 79 (FIG. 2A) that are in communication with the well'bor'e. The outer periphery of the vent tube 75 is laterally spaced relative'td therespective inner .wall surfaces 73 and 81 of the valve elemen t 63 and the packer mandrel 61, and the annularspace' thus 'forrn'e'd'is communicated with the interior of thefpack'er element'13by'several ports 82. Thus it will be appreciated that the valve element 63 is arranged to prevent flow of the fluent material from the chamber 43 FIG. 2A as along as the valve element is retained in its upper position as shown in FIG. 2B. However, when the shear pin 72 fails, the valve to dispose the enlarged element 63 can move downwardly portion 74 of the vent tube 75 thereabove, thereby placing the chamber 43 in communication with the interior of the packer element 13 via the inflation passage and theports 82. Accordingly, the cement slurry can be displaced into the packing element 13 to inflate it and expand it into contact with the well casing wall.

The mandrel 61 carries the inflatable packer element 13.

The packer element 13 can be formed of a suitable flexible or the like facing a downward direction. The swab 'cup 42 defines the upper end of a fluent material chamber 43 that is adapted to contain a suitable material, such as cement slurry which has liquid or flowable properties for a predetermined length of time and which is thereafter capable of hardening or setting up to form a solid mass. The lower end portion of the housing is formed by a latch sleeve 44 having a plurality of circumferentially spaced, downwardly extending latch fingers 45 having enlarged head portions 46 which are normally received within an annular recess 47 formed in the inside wall of the upper end of the body member 12. As shown in enlarged detail in FIG. 3, the latch sleeve 44 has a reduced peripheral portion 49 of the body member 12 and which is sealed with respect to the body member by an O-ring 50. The latch fingers 45 are formed in such a manner that they tend to resile inv wardly to the extent thattherhead portions 46 are disengaged from the recess 47, however the head portions are retained in "engaged positions by the provision of an annular support ring 52 normally located behind the head portions 46. The support 'ring 52 is attached to the lower end of a shifting member 53 which can consist of two L-shaped plates arranged in opposition to oneanother as shown in'FlG. 4. The upper ends of the 1i plates'areeneompassed by' a cap 54 having an outwardly exing arinular lip 55. A coil spring 56is located between the element 13 is secured by clamps sleeve 85 and its upper end similarly secured to an upper slidand impervious material such as neoprene impregnated Dacron clothe. The element 13 can have longitudinal or spiral folds (not shown) therein to reduce its lateral dimensions greatly and enable it to pass through the tubing. To ensure that the element 13 remains folded during running, it can be wrapped with friction tape or the like which will break when subjected to inflation pressures. The lower end portion of the or the like to a lower sliding ing sleeve 86. Suitable seals 87 and 88 fluidly seal between the sleeves and the mandrel 61 to prevent any fluid leakage from the bag 13. The upper sleeve 86 can be initially restrained against sliding motion relative to the mandrel 61 by the provi sion of resilient latch fingers 89 having inwardly extending projections 90 engaging within an external annular recess 91 in the mandrel 61. By exerting an upward pull on the mandrel 61 after the packer element 13 is in forceful contact with the well casing, the projections 90 will be cammed outwardly and disengaged to permit the mandrel to be shifted upwardly for purposes which will be more fully described hereafter.

The central opening 92 of the vent tube 75 and the mandrel bore 93 provide a vent passageway which extends from a plurality of radially extending side ports 94 located below the packer bag 13 to theupper ports 78, 79. The passageway is adapted to be closed off by a vent valve in the form of a vertically movable sleeve 95. The valve sleeve 95 is normally positioned below the side ports 94, and has seal elements 96 and 117 which will seal above and below the ports 94 when the valve sleeve is moved to an upper. position spanning the side ports. Upward movement of the valve sleeve95 is'limited by downwardly facingshoulder98 on the mandrel 61. i

A coil spring 100;is positioned'within the bore 93 of the mandrel 61. The upper end of the spring100 is anchored by a suitable means such as a transverselyextending pin 101. A lower Straight portion 102 of the spring extends downwardly through the bore of the valve sleeve 95 and is provided witha hook 103 atits lowet end..A washer 104or the like is loosely slidable on the springportion l02 ,and the hook and washer are sizedto engage the lower end surfaceof the valve sleeve A timer housing 106 is secured to the lower .end of the packer mandrel 61, The housing- 106 provides a stepped diameter chamber 107, and the lower fend of the housing is closed by'a removable cap 108. A timer mechanism 109-is located within the lower portion of the chamber 107 and has a circular plate 110 which is sealedagainst the shoulder 111 by a packing washer 112. if desired, the void space below the shoulder 1.11 can be filled with a suitable lubricating fluid.v

As .shown in enlarged detail in FIGS, 5-7, the timer mechanism 109 includes a clockwork gear train,113'mounted between fixed side plates11 4 and 115. The motion of the gear train 113 is controlled by. an escapement'116 and balance 117. The main wheel 118 has its shaft 119 provided with a diametrically extending hole 120. The end of a release cored 122 is wrapped several turnsaround the shaft 119 and is provided with a ferrule 123 or the like which is'inserted through the hole 120 as shown in FlG. 7. The release 'cord 122 extends through an aperture 124 in the end plate 110 asshown in FIG. 6 and has. an eye l25which is received on the hook 103 of the spring 100. With the coil spring 100 extended to an energy storing conditionhit will be appreciated that the spring force will apply torque to the shaft 119 of the main wheel 118 of the timer assembly 109. The geartrain 113,escapement 116 and balance 117 will allow the release cord 122 to unwind from the shaft 119 at a highly controlled rate. .Once the cord 122 is unwound and the ferrule 123 reachesajposition n substantial wertical alignment with the longitudinal axis of the timerhousing 106, theferrule will release from thef shaft hole 120 and enable the lowerportion 102 of the spring to travel upwardly. The hook 103 and washer 104 will engage the lower end surface of the valve sleeve 95, thereby shifting the valve sleeve epw'ardly against the stop shoulder 98 and in spanning relationship to the side ports 94. In this condition, the valve sleeve 95 functions to block fluid through the vent passageway.

An alternative embodiment of a timer mechanism is shown in cutaway view in FIG. 8. In this embodiment, the motion wntrol for the gear train 113 is provided by a paddle wheel I126. The paddle wheel 126 replaces the balance in the first ascribed embodiment, and is coupled to the gear train by fifth wheel 127 which replaces the escapement. The fluid friction resisting turning motion of the paddle wheel 126 provides the restraininginfluence which causes the gear train 113 to enable unwinding of the release cord' 122 as previously described at a highly controllable rate.-Consequently,,the timer mechanism is used todelay the valve closing event for a preselected time.

OPERATION In operation, the tool is prepared for lowering into the well by filling the control chamber 18 above the release piston 19 with a suitable hydraulic fluid so that the rod 20 extends into the recess30. The weighted body 38 is forced upwardly, compressing the coil spring 40 until the latch heads 32 are inserted into the recess 30, thereby forcing the rod 20 upwardly until heads fully enter the recess 30. The spring fingers 31 cause the heads 32 to shift outwardly over the shoulder 33, and the rod 20 then shifts downwardly to retain the latch. The coil spring 40 exerts downward force on the weighted body 38. The dump bailer assembly 11 is latched to the body member 12 by inserting the latch sleeve 44within the upper portion 49 and positioning the support ring 52 behind the latch fingers 45so that the head portion 46 are held outwardly in engagement with the recess 47. The valve element 63'is secured in its upper or closed position by the shearscrew.'7 2, and the chamber 43 within the bailer section 11 is filled with predetermined volume of cementitious material. The vent valve closing spring 100 is extended and the hook 103 connected to the eye 125 of the release'cord 122 having its end wrapped several turns around the shaft 119 of the main wheell18 of the timer mechanism 109. The delay involved in closing of the vent passageway is a function of the length of the release cord wrapped around the shaft 119, and the valve closing event can be preselected to occur at a later time, for example, 18 hours. The vent valve 95 is located in its lower position where the side ports 94 are open.

The tool is then lowered downwardly'into the well on the electrical cable W through the tubing T and to a selected setting point within the well casing C below the lowermostend ofthe tubing. At setting depth; an electrical signal .sent through the cable W from the surface will open the solenoid valve 27 in the pump section 10 so the hydraulic fluid can exit from the chamber 18. The force exerted by the spring 22 will move the piston 19 and the rod 20 upwardly, forcing fluid from the chamber 18: As the. rod20 movesupwardly, the

spring fingers 31 are freed to flex inwardly and release from the recess thereby releasing the weighted body 38.

The force of the spring acts to accelerate the weighted body 38 downwardly so that it strikes the piston assembly 41 .in a violent manner. This creates a substantial pressure wave and tend .to gravitate downwardly, thereby forcing the swab cup- 42 downwardly and generating pressure within the chamber 43 to displace the slurry into the element 13. It will be appreciated that the inflation pressure is a function of the weight of the body 38 and the cross-sectional area of the swab" cup 42. The weighted body'38 can'be constructed of suitableheavy or dense'metal such as tungsten or lead and be sized so that a suitable inflation pressure, such as, for example, l525 p.s.i; can be developed within the packer element .13 to expand it into forceful and sealing contact with the well conduit wall as shown in FIG. 9. Since .the upper sleeve 86 is attached to the mandrel 61 by the latch fingers 89 and projections 90, the lower sleeve 85 will slide upwardly along the mandrel during expansion of the packer element 13.

Afterthe packer element 13 is fully inflated, it forms, in effect, a platform or bridge in the well bore upon which additional cement slurry can be deposited. This can be accomplished by manipulation of the tool including an upward pull on the cable W. The friction betweenthe packer element 13 and the casing C will enable an upward force on the mandrel 61 to cause release of the projections 90 so that the mandrel ,can be shifted upwardly relative to the packer element 13,

, thereby exposing the inflation ports 82 to the well annulus above the bag as shown in FlG. 10. Movement of the inflation ports above the seals 88 on the sleeve 86 traps the inflation pressure within the expanded packing element and permits dumping the remainder of the cement slurry within the chamber 43 on top of the element 13. When the swab cup 42 Additional dump bailer runs can be made as desired to increase the overall length of the cement plug.

During the time that the cement is hardening, the vent passageway formed by the vent tube and mandrel bores 92 and 93 remains in open condition as shown in FIG. 9 so that any produced fluids entering the casing C from below'the packer element 13 can pass upwardly therethrough and enter the well annulus above the plug through the upper ports 78, 79., Accordingly, it will be appreciated that such fluids will have no tendency to form channels either around the packer element 13 or through the material on top of it, which disturbances may otherwise destroy the effectiveness of the plug to hold pressure. The timer mechanism 109 has, of course, been running ever since the same was initiated at the top of the, well bore. At the end of the preselected delay time, the release cord 122 will have unwound from the shaft 119 so that the ferrule 123 will release as previously described. The spring 100- willthen force the valve sleeve 95 upwardly to closed position to blockall vertical movement of fluids within the well casing C.

A new and improved apparatus has been disclosed for effectively plugging a well conduit. In accordance with the present invention, the plug can be lowered through tubing and then set or-formed in casing or open hole without removing the smaller tubingfrom the well. The invention is arranged in a manner for-.controllably bypassing or venting fluid flow while the plug iswforming to prevent disturbance of the plug. After a preselected time lapse, the vent passage is automatically closed; off without the need for further manipulations or .operations from the top of the well bore.

Since certain changes and modifications may be made in the disclosed; embodiment of the invention without departing fromthe concepts involved, it is the aim of the appended claims to'icover all such changes and modifications which fall within the true spirit and scope of the present invention.

passageway; spring means disposed in an energy storing condition: and adapted to shift said valve means to closed position .4. .means for. retaining said spring means in energy storing condition; andmeans including a timer for disabling said retaining means to enable said spring means to shift said valve means to closed position only after a preselected time lapse.

2. In a welltool for use in providing a plug in a well bore: an elongated body member; means carried by said body member and adapted to be extended into contact with a surrounding well-bore wall to provide a bridge across the well bore; a

, passageway for providing a fluid flow course between locations in-communication .with the well bore above and below said bridge;- normally open valve means adapted to be shifted axially of said support to a position closing off said -..passageway; means including an extended spring that is capa- -bleof-.contracting: movement for shifting said valve means to the passageway closing position; means for retaining said spring inextended position; and delay means operable only after a. preselected time lapse for disabling said retaining means so that contracting movement of said spring means can function to shift said valve means to said passageway closing position.

..; 3.,In a well too] for use in providing a plug in a well bore: an elongated body member; packing means carried by said body member and adapted to be expanded into contact with a well bore wallggafluid passageway extending in said body member between locations in communication with the well bore above and below said packing means; valve means shiftable upz-wardly. and downwardly in said passageway between positions closing and opening said passageway to fluid flow; means for shifting said valve means from open to closed position; and delay means for preventing operation of shifting "means until the expiration of a preselected time; said delay means then enabling said shifting means to move said valve means from said open position to said closed position.

4. The well tool of claim 3 wher'e'iri"'"s'a'id passageway has a terminal portion provided by laterallyiextending port'means, said valve means comprising a sleeve'h'avin'g seal means engageable with wall surfaces of said passageway above and below said port means. 3

5. In a well tool for use in providing a plug in a well bore: an elongated body member; an inflatable packingaelement adapted to be expanded into contact with a well bore wall;

means for inflating said packing element; a flow passage extending in said body member between locations in communication with the well bore above and below said packing element; a valve element shiftable between positions opening and closing said passage; means for shifting said valve element from open position to closed position; and clock means for delaying operation of said shifting means until after the expiration of a preselected time delay.

6. The well tool of claim 5 wherein said shifting means includes an extended spring having one end portion anchored in said passage; means for coupling another portion. ofsaid spring to said valve means so that contraction of saidspring can shift said valve means, said clock means beingcoupled to said other portion in a manner to prevent contraction of; said spring means during said time delay. v

7. the well tool of claim 5 wherein said clock means includes a shaft; and further including release means coupled between said shaft and said spring means, rotation of said shaft a preselected number of revolutions functioning to release-said release means and enabling contraction of said spring.

8. The well tool of claim 5 wherein said clock means in cludes a shaft; and further including a flexible release cord having one end connected to said spring and its other end wound around said shaft and releasably connected thereto, rotation of said shaft a preselected number of revolution functioning to release said cord and enable contraction of said spring.

9. The well tool of claim 5 wherein said clock means includes a transversely extending shaft having a diametrically extending hole therein; and further including a flexible release cord having one end portion connected to said spring and it's other end portion wound around said shaft; a ferrule on said other end portion inserted in said hole, whereby rotation of said shaft by an amount sufficient to unwind said cord an to axially align said ferrule with said passage enabling release of said ferrule from said shaft and contraction of said spring.

10. In a well tool for use in providing a plug in awell bore: an elongated body member; an inflatable packing element adapted to be expanded into contact with a well bore wall; means for inflation said packing element; a flow passage extending in said body member between locations in communication with the well bore above and below said packing element; a valve element shiftable between positions opening and closing said passage; normally extended spring means capable of contracting movement to shift said valve element from open to closed position; and restraining means for controlling contracting movement of said spring means to delay closing of said valve element.

11. The well tool of claim 10 wherein said restraining means includes a gear train coupled to said spring means, and means for controlling the motion of said gear train.

12. The well tool of claim 11 wherein said controlling means includes an escapement and a balance.

13. The well tool of claim 1 I wherein said controlling means includes a paddle wheel immersed in fluid.

14. In a well tool for use in providing a plug in a well bore: a body member; expansible bridging means carried by said body member and adapted to be expanded into contact with a surrounding well bore wall to provide a bridge across the well cle; a fluid passageway extending in said body member between locations in communication with the well bore above and below said bridging means; normally open valve means adapted to be shifted to a position closing off said passageway; means for shifting said valve means fromopen to closed position; and delay means for preventing operation of said shifting means until the expiration of preselected time delay, said delay means then enabling said shifting means to shift said valve means from open to closed position.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,556,215 Dated January 19, 1971 Inventor(s) Nevyl G. Owens It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 8, "plugging" should read plug in Column 3, line 64, after "portion" insert 48 which is received within the upper end portion Column 4, line 37 "Fig. 2A" should read (Fig. 2A) --J;. 1in -.49 "clothe" should read cloth Column 5, ine 28, "cored" should read cord Column 7, line 42, cancel "n". Column 8, line 31, "5" should read 6 line 36, "5" should read 6 line 43, "5' should read 6 Signed and sealed this 14th day of November 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM P0-1050 (10-69) uscoMM-Dc 60375-P60 

1. In a well tool for use in providing a plug in a well bore: an elongated body member; means carried by said body member and adapted to be extended into contact with a surrounding well bore wall to provide a bridge across the well bore; a passageway for providing a fluid flow course between n locations in communication with the well bore above and below said bridge; normally open valve means adapted to be shifted axially of said support to a position closing off said passageway; spring means disposed in an energy storing condition and adapted to shift said valve means to closed position means for retaining said spring means in energy storing condition; and means including a timer for disabling said retaining means to enable said spring means to shift said valve means to closed position only after a preselected time lapse.
 2. In a well tool for use in providing a plug in a well bore: an elongated body member; means carried by said body member and adapted to be extended into contact with a surrounding well bore wall to provide a bridge across the well bore; a passageway for providing a fluid flow course between locations in communication with the well bore above and below said bridge; normally open valve means adapted to be shifted axially of said support to a position closing off said passageway; means including an extended spring that is capable of contracting movement for shifting said valve means to the passageway closing position; means for retaining said spring in extended position; and delay means operable only after a preselected time lapse for disabling said retaining means so that contracting movement of said spring means can function to shift said valve means to said passageway closing position.
 3. In a well tool for use in providing a plug in a well bore: an elongated body member; packing means carried by said body member and adapted to be expanded into contact with a well bore wall; a fluid passageway extending in said body member between locations in communication with the well bore above and below said packing means; valve means shiftable upwardly and downwardly in said passageway between positions closing and opening said passageway to fluid flow; means for shifting said valve means from open to closed position; and delay means for preventing operation of shifting means until the expiration of a preselected time, said delay means then enabling said shifting means to move said valve means from said open position to said closed position.
 4. The well tool of claim 3 wherein said passageway has a terminal portion provided by laterally extending port means, said valve means comprising a sleeve having seal means engageable with wall surfaces of said passageway above and below said port means.
 5. In a well tool for use in providing a plug in a well bore: an elongated body member; an inflatable packing element adapted to be expandeD into contact with a well bore wall; means for inflating said packing element; a flow passage extending in said body member between locations in communication with the well bore above and below said packing element; a valve element shiftable between positions opening and closing said passage; means for shifting said valve element from open position to closed position; and clock means for delaying operation of said shifting means until after the expiration of a preselected time delay.
 6. The well tool of claim 5 wherein said shifting means includes an extended spring having one end portion anchored in said passage; means for coupling another portion of said spring to said valve means so that contraction of said spring can shift said valve means, said clock means being coupled to said other portion in a manner to prevent contraction of said spring means during said time delay.
 7. the well tool of claim 5 wherein said clock means includes a shaft; and further including release means coupled between said shaft and said spring means, rotation of said shaft a preselected number of revolutions functioning to release said release means and enabling contraction of said spring.
 8. The well tool of claim 5 wherein said clock means includes a shaft; and further including a flexible release cord having one end connected to said spring and its other end wound around said shaft and releasably connected thereto, rotation of said shaft a preselected number of revolution functioning to release said cord and enable contraction of said spring.
 9. The well tool of claim 5 wherein said clock means includes a transversely extending shaft having a diametrically extending hole therein; and further including a flexible release cord having one end portion connected to said spring and it''s other end portion wound around said shaft; a ferrule on said other end portion inserted in said hole, whereby rotation of said shaft by an amount sufficient to unwind said cord an to axially align said ferrule with said passage enabling release of said ferrule from said shaft and contraction of said spring.
 10. In a well tool for use in providing a plug in a well bore: an elongated body member; an inflatable packing element adapted to be expanded into contact with a well bore wall; means for inflation said packing element; a flow passage extending in said body member between locations in communication with the well bore above and below said packing element; a valve element shiftable between positions opening and closing said passage; normally extended spring means capable of contracting movement to shift said valve element from open to closed position; and restraining means for controlling contracting movement of said spring means to delay closing of said valve element.
 11. The well tool of claim 10 wherein said restraining means includes a gear train coupled to said spring means, and means for controlling the motion of said gear train.
 12. The well tool of claim 11 wherein said controlling means includes an escapement and a balance.
 13. The well tool of claim 11 wherein said controlling means includes a paddle wheel immersed in fluid.
 14. In a well tool for use in providing a plug in a well bore: a body member; expansible bridging means carried by said body member and adapted to be expanded into contact with a surrounding well bore wall to provide a bridge across the well bore; a receptacle adapted to contain a fluent medium; passage means communicating said receptacle with the interior of said bridging means; pump means including a piston member movable downwardly in said receptacle for forcing said fluent medium through said passage means and into the interior of said bridging means to expand said bridging means; latch means between said receptacle and said body member for releasably coupling said receptacle to said body member; release means cooperating between said piston member and said latch means for releasing said latch means after said piston means has forced said fluent mEdium from said receptacle; a fluid passageway extending in said body member between locations in communication with the well bore above and below said bridging means; normally open valve means adapted to be shifted to a position closing off said passageway; means for shifting said valve means from open to closed position; and delay means for preventing operation of said shifting means until the expiration of preselected time delay, said delay means then enabling said shifting means to shift said valve means from open to closed position. 